Does Soil Health Improve Milk Production?
Several dairy farmers have been asking the question: Does improving soil health improve dairy cow health and dairy cow performance? Either higher milk yields, higher components, or just overall herd health? It’s a tough and complicated question to prove definitely, but the answer appears to trend in the direction of YES to all of the above.
Milk is about 87% water and 13% solids. As it comes from the cow, the solid portion is about 3.7% fat and 9% solids not fat. Milk has fat soluble Vitamins A, D, E, K. The solids not fat portion is protein, carbohydrates (primarily lactose) and minerals including calcium and phosphorus. Milk is a good rich, dense food source especially for young growing children but also for older adults to avoid calcium deficiency.
Researchers at Cornell University compared three fields, one unmanured and two that were manured at three different locations. The number of sites is low so our confidence in the data is rather limited. This was research conducted by Cornell Pro-Dairy on Corn Silage Hybrid Education (2023). Manured fields are generally considered healthier because they have higher microbial populations and higher nutrient levels. The manured fields had plants that are healthier with bigger roots, shoots, and slightly bigger ears.
They tracked rainfall and nitrogen application to the corn silage fields. They were not significantly different but the results were different. Two manured fields had .5% and 1.3% higher crude protein levels in the corn silage feed. Higher butter fat and crude protein levels have a positive impact on dairy components. Dairy components are the amount of water, fat, protein, lactose and minerals which are separated concentrated or modified for certain milk products. Farmers usually get paid a base price for milk plus bonuses for higher dairy components. Think high butterfat premium ice cream! Premium ice cream costs more but tastes better due to higher butterfat content.
In the study, the starch content of the manured fields was higher and the fiber digestibility improved. As the starch content increases in the feed, that decreases the overall rumen pH and increases beneficial microbes in the rumen which support higher fat synthesis in the milk (just think yummy). The increased starch means the energy density of the food increases so the cow has more energy for basic living (maintenance) plus milk production. In other words, the cow can maintain her weight while producing more milk. A cow can only consume so much, so healthy denser, energy rich food means more milk with higher components. Enhanced rumen fertilization for healthy microbes needed to produce milk. On average, the cows yield of raw milk increases 5-10%.
Other attributes of healthy feed for dairy cows are improved fiber digestibility or increased NDFD (Neutral Detergent Fiber Digestion) which measures the digestibility of plant cell walls in dairy cattle. High fiber diets (greater than 40%) increase acetate in the dairy cow which leads to increased milk fat.
Healthy soils have more nutrients and some of these extra nutrients end up in the milk. Balanced soil nutrition leads to healthy milk which if humans drink or eat it leads to healthy human nutrition also. The corn silage fields had an 8-ton advantage in corn silage yields. With added components and starch, dairy farmers had to feed less supplement worth $270 per acre.
Dairy herd health was better for cows fed healthy nutrient rich corn silage. The healthy feed prevented rumen acidosis and improved hoof health. The name of the article: Soil Health & Corn Silage Performance Comparing Grain and Dairy Field Systems by Joe Lawrence and Kristen Workman, Cornell University, March 12, 2025.
In a completely separate study, Agro Liquid (a liquid fertilizer made in Michigan) was used to replace commercial synthetic fertilizer. Commercial fertilizers are known to be much higher in salt content which can be detrimental to soil life, particularly soil microbes. Salts are just atoms or ions with positive and negative charges which tend to attract water and desiccate the microbial living environment.
The Agro Liquid fertilizer cost $100 per acre but produced 8400 pounds more milk per acre. At $.15 per pound of milk that is $1260/acre for the corn silage grown on that field. It replaced about the equivalent of 2900 pounds of corn meal fed to dairy cows because the corn silage had a higher quality and energy density. That is worth about $270 for not having to feed the corn meal as a supplement. It replaced about 8 pounds of ground corn per dairy cow. Overall, these type of studies are hard to prove but the overall trends are positive and in the right direction.
